Effect of extraction temperature, time and volume of diluent on oil yield from ginger (<i>Zingiber officinale</i>) in a batch-mode process

Abstract

This study focuses on modelling, optimizing and examining the effect of extraction temperature, volume of diluent and extraction time on the yield of oil from Zingiber officinale (ginger) using a batch-mode solvent extraction process with ethanol as solvent. Fresh ginger seeds were obtained from a local vendor, washed with distilled water and sun-dried. The dried sample was then milled to further reduce the particle size. A four-level-three-factor Doptimal approach was used for designing the experiments and for developing a statistical model for the optimization of the process variables. A quadratic model was developed for modelling and optimization of the extraction parameters. The model was significant with p-value less than 0.0001 and the "Lack of Fit" p-value was 0.1019, which means that the lack of fit was insignificant. A high R² value of 0.983 by the model shows that the model was able to adequately represent the actual relationship between the variables studied. Extraction temperatures, volume of diluent and extraction time were found to have significant effect on the yield of oil from ginger. The optimum conditions predicted by the model were 82.22⁰C extraction temperature, 300 ml volume of diluent, and 30 minutes extraction time. The predicted yield was 21.451% and the results obtained from three replications gave an average yield of 20.533% which was close to the predicted value.

Keywords: Ginger, extraction, process parameters, optimisation, D-optimal, RSM